Protective relay system for synchronous machines



Aug. 8, 1939. M, MlcHEL 2,169,029

PROTECTIVE RELAY SYSTEM FOR SYNCHRONOUS MACHINES Filed Jan. 16, 1937 WITNESSES: HJVENTOR jig/@2825 Mic/72. 4 i i 0 f g4 ATTO 115 EY Patented Aug. 8, 1939 I I UNITED STATES PATENT orl-"lca rno'rnc'nva RELAY SYSTEM Fort SYNCHRONOUS Machines Mathias Michel, Wauwatosa, Wis., asslgnor to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsylvania Application January 16, 1937, Serial No. 120,928 9 Claims, (Cl. 172-289) My invention relates, generally, to a relay systion with reference to the accompanying draw- .tem, and, more particularly, to a locked rotor ing. in which: protective relay system for synchronous ma- Figure 1 is a diagrammatic illustration of the chines. elements of structure of the 'preferred'embodi- 5 The object of my invention, generally stated,- ment of my invention in their cooperative rela- 5 is to provide a device for preventing sustained tionships, in which the co t relay System 18 energization of a synchronous machine in the actuated by an interrupter driven by the shaft event that the rotor looks or fails to rotateupon of the synchronous machine, and being energized. Fig. 2, which is a modification in which the re- A more specific object of my invention is to lay system is actuated by impulses derived from 10 upon being energized.

provide a relay system responsive to the rotating combining the frequency applied to the. alteror standstill condition of a synchronous machine nating current windings of the machine with the for preventing sustained energization of the mafrequency induced in the field Wind-1118 0f the chine in the event that the rotor fails to rotate machine.

7 Referring to Fig. 1, I have shown the alter- 15 A further object of my invention is to provide nating current or stator winding 3 of a synchroa protective relay system which shall function nous machine connected to be energized from to open the starting switch of a synchronous maalternating current power Source y chine in the event that themachine fails to roclosing circuit breaker 5. Circuit breaker 5 is tate at a predetermined speed within a predeclosed by energizing its closing 0 11 5 r the 20 termined time after the starting switch has been source of control powerrepresented by conducclosed. ltorsA-B through a contactor 1. This contac- Another object of my invention is to provide tor may be a hand switch or a'remotely cona relay system which shalliunction to indicate trolled switching device such asis c mm nly d 5 whether or not a synchronous machine is rotat in automatic sub-static ing at a predetermined time after the machine. Actuation of closing coil 6 also causes closure is energized. I of contact members Iii to supply potential to the A still further object of my invention is to prorelay System from the Source 01 001113101 current vide a locked rotor protective relay system which 'A- may be constructed for the most part of stand- A timing device is provided in relays is so ard relays and switching apparatus and which and i1. Relay I3 is a vibra in r l y w i may be easily installed and operated. I when energized, closes contact I! to energize re- A further object of my invention is to-provide lay t, whic s a 51 w po e a when a locked rotor protective relay system which shall lay t s d e e s ed. armature l8 a es be inexpensive to manufacture and install .and ternately closing contacts I4 and ii for a period which will require no mechanical connection ep n g upon h weight of the armature and with the machine with which it is associated, its sprin 11990" Other objects of my invention will be apparent T e time delay for release of relay I6 s so from the description of the invention which is designed as to prevent the "mature of relay 40 to follow and the appended claims.- mm fimppmfl F the Pemd between the 40 .In practicing my invention in its preferred brealimg at contact-H and making at and fo m a relaysystem' which gncmdes timing vice versa. It will be noted that contact memlays and other relays responsive to the condition relay are chsed q \the initial of rotation or standstill of the rotor of a syn; -closure of contact ii-by energization of relay I3. chronous machine which it is desired to start, is The closure of (iontact members-'mlista%shes 45 set into operation when the starting switch of circuit to relay through Contact e purpose of contact members [9 is to positively dethe machine is closed and functions to the energize relay it once vibrating. relay l3 begins starting switch in the event that the rotor of to vibrate at such 10w amplitudes as to fan 9 t machme does rotate-appreciably within positively maintain circuits through contacts i4 a time after closing the starting switch which and pends upon the time delay of h imin Upon the initial energization of relay ii, conlays. g tact members 20 are closed to energize relay ll Further objects and advantages of my invenand to thereby open contact members 2|. Thetion will be apparent from the following descripopening of contact members 2| de-energizes re- 55 "Kill open. At the end of the 2, lay it to start the timing period determined by relay is,

At the time. that relay is was energized, its contact members 22, control circuit for the trip 001123 of circuit breaker 5 were open, thus rendering this trip circuit inoperative. At the end of the vibrating period of armature l8, relay It will again be deenergized to allow contact membersZ? to close.

An interrupter 8 is provided for alternately making and breaking the circuit to relay 9,

whereby contact members ii are closed and contact members l2 opened when relay 9 is de-energized, and contact members H opened and I2 closed when relay 9 is energized. Auxiliary control relay Z lis controlled by contact members ii of relay 9 and contact members 25 of -relay ll. When energized, relay 26 closes its own holding circuit through contact members 26 and 25.

Auxiliary control relay 21 is controlled by contact members 12 of relay 9 and contact members '25 of relay ll. When energized, relay 2i closes its own holding circuit through contact-members 28 and 25.

A control circuit for the trip coil 23 of circuit breaker 5 is provided through contact members 29 and 3B of relays 2d and 21, respectively, in parallel, contact members 3i of relay ll and contact members 22 of relay it. i

An indicator 32 which may be a lamp or any other enunciator is controlled by a series circuit which includes contact members '33 and contact members 34 of relay 2?.

In the operation of my device, when it is desired of relay 25 to start the synchronousmachine, control switch l is closed to energize the closing coil for circuit breaker 5 thus connecting the alternating current winding of the machine with the power source conductors X--Y-Z. When ilsosed, contact members it close to energize relay Energization of relay It starts the timing relay system by causing closure of contact l5, thus energizing relay l6. Energization of relay it causes closure of contact members 2t which energizes relay ll, causing contact members 2! to open, which, in turn, de-energize relay it.

When relay i3 is de-energized, armature it will oscillate to alternately open and close contacts l6 and 115, thus keeping relay l5 intermittently energized and causing relay i6, by virtueof its slow release characteristic, to hold its contact members l9 and 20 closed and its contact members 22 V oscillation period of armature l8, relay it will be de-energized, allowing contact members l9 and Eli to open and causing contact members 22, to close.

It will be noted thatrelay ii is held energized through its own contact members 25 after it isinitially energized by the closure of contact menibers 2@. This circuit will be maintained even after contact members 20 are opened by the energization of relay it.

Assuming that, when the sychronous machine and the relay control circuit are energized, the interrupter is in the position shown in the drawing, and further assuming that for some reason the machine fails to rotate, it will benoted that which are connected in the members 28 and El having'been brought about by switch 5 isshown in a position .is the resistance teristics of vibrating relay it, made through the trip coil 23 of circuit breaker ,5, causing the circuit breaker to de-energize the synchronous machine. This circuit comprises contact members 22, 3| and 30 and coil 23.

If, when the synchronous machine is energized and fails to rotate the'interrupter is in such a position as to cause energization of relay 9, contact members l2 of relay 9 will be closed and a cricuit will be established through contact members l2 and 25 to energize relay 2?. Relay 21 will open contact members 30 and close contact 3%, the closure of contact members 28 establishing a holding circuit for relay 21 through contact members 2% and 28.

Under these conditions, trip coil 23 will be energized through a circuit which comprises contact members 22, Si and 29 and coil 23. This will cause circuit breaker 5 to open to de-energize the synchronous machine.

If the synchronous machine starts to rotate properly when it is energized, interrupter B will be rotated and this will cause alternate energization and de-energization of relay 9. In the deenergized period of relay 9, relay 2 3 will be energized as explained above and will hold itself ena circuit will be ergized causing contact members 29 to be held.

open and contact members 33 to be held closed.

In the energized periodoi relay 9, relay 2i will be energized as explained above and will hold itselft energized through its holding circuit. This will cause contact members 39 to be held open and contact members 3 3 to be held closed.

Under these conditions, when the predetermined time governed by the characteristics of vibrating relay l3 has elapsed, contact members 22 will close, but the energization of relays 26 and the rotation of interrupter 6, both contact members 29 and .36 will be open, thus preventing energization of the trip coil 23 for circuit breaker 5.

When relays 2t and El are both held energized because of the rotation of the machine, their con, tact members 533 and 343 will be held closed, causing energization of the indicator 32, thus indicating to the operator that the machine is starting chronous machine controlled by a switch 3% which may be a hand operated switch or any switch automatically controlled by predetermined conditions of operation of the machine. This switch is in which it connects a resistance Si in shunt with the field winding. This which is commonly used as a discharge resistance for a field winding when breaking the energizing current of such a field. In the other position of the switch 36, the field winding would be connected to a source of direct current which would energize the field winding for normal operation of the synchronous machine;

A transformer 35, having opposed windings 38 and 39 and an auxiliary winding lll, is provided. Winding (it is connected to the leadsof the synchronous machine so as to be energized by the of Fig. 2, the relay system of,

Like reference characters refer to alternating current which energizes the machine.

Transformer winding 39 is connected across the field winding 4. Auxiliary winding 40 is connected in circuit with afull wave rectifier unit 4| and this rectifier unit is connected to energize relay coil 9.

In the operation of the modification of Fig. 2, when the circuit breaker 5 is closed transformer coil 38 is energized at the frequency of the power source. If the synchronous machine fails to rotate, an electromotive force will be induced in the field winding 4 which will be of the same fre quency as that which is applied to the alternating current winding 3 ofthe synchronous machine. This will cause energization of transformer coil 39 at the frequency of the power source,

' Energization of both of the opposing coils 38 and 38 at the same frequency will cause them to neutralize each other in their effect on the transformer core and no resulting electromotive force will be induced in auxiliary transformer coil 40.

' Under theseconditions, relay coil 9* will remain de-energized and the relay system will operate to trip circuit breaker 5, as was explained hereinbefore under the conditions in which the relay 9 was held de-energized by failure of the interrupter 8 to rotate. a

a If the synchronous machine starts to'rotate properly when it is energized an electromotive force will be induced in field Winding 4 at a frequency which is less than the'frequency applied to the alternating current winding 3 of the synchronous machine by an amount which is determined by the ratio ofthe speed of the machine to its synchronous speed. In this manner, the power source frequency will be impressed upon transformer coil 38, while an electromotive force of a lower upon the transformer coil 39.

The resultant'of the fluxes in the transformer- 35, due to the different frequencies impressed upon it, will cause an electromotive force to be induced in auxiliary coil 40 which corresponds to the difference between the two frequencies; When the electromotive force induced in transformer 'coil 40 has been rectified, it will appear on relay coil 9 as a series of direct current impulses whose frequency will be'the difference of the frequencies impressed upon transformer coils 38 and 39.

' The result of impressing the impulses on relay 9 will be the alternate opening and closing of the circuits to relays 24 and 21 through contact members H" and I2. By thus operating both. relays 24 and 21 within the time period determined by the vibrating'relay l3, contacts 29 and 30 are open and held open so as to prevent energization of trip coil 23.

It will thus be seen that I have provided an inexpensive and reliable means for protecting a synchronous machine by de-energizing the winding of the machine in the event that the machine fails to rotate within a predetermined time after I it is energized.

' In compliance with 'th requirements of the patent statutes, 1 have shown and described herein a preferred embodiment of my invention and a modification thereof. It is understood, however, that the invention is not limited to the precise construction shown and described, but iscapable of modification by one skilledin the art, the embodiments herein shown being illus-- trative of the principles of my invention. a I claim as my invention:

frequency will be impressed 1. In a locked rotor protective system for a synchronous machine. in combination. a starting switch for connecting the machine to be energized from a source of power, auxiliary switch means, means for closing the auxiliary switch means when the starting switch is closed, a vibrating relay having means for making a circuit when the rela is energized and having means for alternately breaking and making said circuit for a predetermined time after being de-energized and for holding said circuit open after said predetermined time, circuit means for energizing said vibrating relay when the auxiliary switch means is closed, a slow release relay connected to be energized by said vibrating relay circuit making means and having a release time greater than the time between breaking and making of the vibrating relay circuit control means, a first relay connected in circuit to be energized when the slow release relay is energized, back contact members operated by said first relay to be opened when said first relay is energized, said back contact members being connected in circuit to control the energization of said vibrating relay, said first relay having front contact members connected. in circuit to hold said first relay energized, a second relay, a third relay and a fourth relay, means governed by the rotation of the machine for alternately energizing and de-energizing said fourth relay when the machine is rotating and for holding said fourth relay either energized or de-energized when the machine is not rotating and the said starting switch is closed, a back contact member controlled by said fourth relay connected in circuit with said front contact members of said first relay and said second relay to control said second relay, having front contact members connected in circuit with said front contact members of said first relay to hold said second relay energized,

said second relay said fourth relay having front contact members connected in circuit with bars of said first relay and said third relay to control said third relay, said third'relay having front contact members connected in circuit with said front contact members of said first relay to hold said third relay energized. said second and the front contact memthird relays having back contact members which contact members of said second relay in one branch and the back contact members of said third relay in the other branch.

'2. In a locked rotor protective system for a synchronous machine, in combination, a starting switch for connecting the machine to be energized from a source of power, auxiliary switch means, means for closing the auxiliary switch means when the starting switch is closed, a vibrating relay having means for making a circuit when the relay is energized and having means for alternately breaking and making said circuit for a predetermined time after being de-energized and for holding said circuit open after said predetermined time, circuit means for energizing said vibrating relay when the auxilary switch means is closed, a slow release relay connected to be energized by said vibrating relay circuit making means and having a release time greater than the time between breaking and making of the vibrating relay circuit control means, a first relay connected in circuit to be energized when the slow' release relay is energized, back contact members operated by said first relay to be opened when said first relay is energized, said back contact members being connected in circuit to control energization of said vibrating relay, said first relay having front contact members connected in circuit to hold said first relay energized, a second relay, a third relay and a fourth relay, means governed by the rotation of the machine for alternately energizing and de-energizing said fourth relay when the machine is rotating and for holding said fourth relay either energized or de-energized when the machine is not rotating and the said starting switch is closed, a back contact member controlled by said fourth relay connected in circuit with said front contact members of said first relay and said second relay to control said secondrelay, said second relay having'front contact members connected in circuit with said front contact members of said first relay to hold said second rlay energized, said fourth relay having front contact members con.

nected in circuit with the front contact members of said first relay and said third relay to control said third relay, said third relay having front contact members connected in circuit with said front 'contact members of said first relay to hold said third relay energized, said second and third relays having back contact members which are opened when said second and third relays areener ized, a second front contact member controlled by said first relay, a back contact member controlled by said slow release relay, opening means for said starting switch, a circuit including said opening means, said backcontact members of said slow release relay and said second front contact members 0f,said first relay in series with a. parallel circuit having the back contact members of said secondrelay in one branch and the back contact members of said third relay'in theother branch, said second and third relays having other back contact members in series circuit with an indicat--.

ing device.

3. In a locked rotor protective systemlfor a synchronous machine, in combination, a starting switch for connecting the machine to be energized from a source of power, auxiliary switch means,

means for closing the auxiliary switch means when the starting switch is' closed, a vibrating relay having means for making a circuit when the relay is energized and having means for alternately breaking and making said circuit for a predetermined time after being de-energized and for holding said circuit open after said predetermined time, circuit means for energizing said vibrating relay when the auxiliary switch means is closed, a slow release relay connected to be en-, ergized by said vibrating relay circuit making means and having a release time greater-than the time betweenbreaking and making of the vibrating relay circuit control means, a first relay connected in circuit to be energized when the slow release relay is energized, back contact members operated by said first relay to be opened when said first relay is energized, said back contact members being connected in circuit to control energization of said vibrating relay, said first relay havingfront contact members connected in circuit to hold said first relay energized, a second relay, a third relay and a fourth relay, means a first relay,

.tact members controlled said trip device and said timing relay means. means third relay,

back contact members controlled by governed by the rotation of the machine for alternately energizing and de-energizing said fourth relay when the machine is rotating and for holding said fourth relay de-energized when the machine is not rotating and the said starting switch is closed, a back contact member controlled by said fourth relay connected in circuit with said relay to hold said third relay energized, said sec- 0nd and third relays having back contact mem-' bers which are opened when said second and third relays are energized, a second front contact member controlled by said first relay, a back contact member controlled by said slow release relay, opening means for said starting switch, a circuit including said opening means, said back contact members of said slow'release relay and said second front contact members of said first relay in series with a parallel circuit having the back contact members of said second relay in one branch and the back contact members of said third relay in the other branch.

4. In a protective relay system for a synchronous, machine, a starting switch for the machine, timing relay means, means for energizing the timing relay when the starting switch is closed, means governed by the rotation of the machine for causing impulses to be impressed upon the .coil of said first relay, a second relay,

said firstrelay having back contact members con-- nected in circuit with said second relay, relay, said a third first relay having front contact members connected in circuit with said third relay, circuit means for holding said second and third relays energized after their initial energization through the contact members of said first relay, a trip means for the circuit breaker, back conby said timing relay means which are closed at a predetermined time after the initial energization of said timing relay means, said back contact members of said second and third relays being included in circuit with back contact members of said timing relay means in such a manner as to complete a circuit to energize said trip device when the back contact members of the timing relay close in the. event that either the second or third relay has not been energized as a result of rotation of the synchronous machine.

5. In a protective relay system for a synchronous machine, a starting switch for the machine, for energizing the timing relay when the starting switch is closed, a first relay, means governed by the rotation of the machine for causing impulses to be impressed upon thecoii of said first relay, a second. relay, said first relay having back contact members connected'in circuit with said second relay, a said first relay having front contact members connected in circuit with said third relay, circuit means for holding said second and third relays energized after their initial energization through the contact members of said first relay, a trip means for the circuit breaker, said timing bers on said second and third relays so that said indicating means will be energized in the event that the machine rotates.

6. In a protective system' for an electrically driven rotating machine, in combination, a startthe timing means. 7. In a locked synchronous motor, in combination, a starting rotates and thus pulsating voltage within the time the timing means.

8. In a protective system for a synchronous motor, in combination, a starting switch for the motor, timing means responsive to the closure of the starting switch for opening the starting switch produces said determined by that the rotor rotates and pulsating voltage within the the timing means. I

9. In a protective starting system for a synchronous motor, in combination, a starting switch for energizing the machine, timing means respono the closure of the starting switch for opening the starting switch at a predetermined time after the starting switch is closed, impulse generating means rendered operative by the closure of the starting switch whereby the rotation of the machine produces a series of impulses, and relay means controlled by said impulses for rendering the timing means for opening the said starting switch inoperative in the event that the machine thus produces said time determined by rotates within the time determined by the timing means.

M ATHIAS MICHEL. 

